God must produce something in the creature. But
this is not so; because this action does not give being to the
creature, since being is not given to that which already is: nor does
it add anything new to the creature; because either God would not
keep the creature in being continually, or He would be continually
adding something new to the creature; either of which is
unreasonable. Therefore creatures are not kept in being by God.

_On the contrary,_ It is written (Heb. 1:3): "Upholding all things by
the word of His power."

_I answer that,_ Both reason and faith bind us to say that creatures
are kept in being by God. To make this clear, we must consider that a
thing is preserved by another in two ways. First, indirectly, and
accidentally; thus a person is said to preserve anything by removing
the cause of its corruption, as a man may be said to preserve a
child, whom he guards from falling into the fire. In this way God
preserves some things, but not all, for there are some things of such
a nature that nothing can corrupt them, so that it is not necessary
to keep them from corruption. Secondly, a thing is said to preserve
another _per se_ and directly, namely, when what is preserved depends
on the preserver in such a way that it cannot exist without it. In
this manner all creatures need to be preserved by God. For the being
of every creature depends on God, so that not for a moment could it
subsist, but would fall into nothingness were it not kept in being by
the operation of the Divine power, as Gregory says (Moral. xvi).

This is made clear as follows: Every effect depends on its cause, so
far as it is its cause. But we must observe that an agent may be the
cause of the _becoming_ of its effect, but not directly of its
_being._ This may be seen both in artificial and in natural beings:
for the builder causes the house in its _becoming,_ but he is not the
direct cause of its _being._ For it is clear that the _being_ of the
house is a result of its form, which consists in the putting together
and arrangement of the materials, and results from the natural
qualities of certain things. Thus a cook dresses the food by applying
the natural activity of fire; thus a builder constructs a house, by
making use of cement, stones, and wood which are able to be put
together in a certain order and to preserve it. Therefore the _being_
of a house depends on the nature of these materials, just as its
_becoming_ depends on the acti